1. Field of the Invention
The invention relates to light intensity detecting methods and devices, and display devices and storage media using the same, detecting light intensity according to pulse duration of a pulse signal output from a light sensor.
2. Description of the Related Art
Methods for adjusting display illumination according to environmental light intensity and devices thereof are applied in vehicle and portable display devices. For example, Japanese Patent Application Laid-Open No. 2001-522058 discloses a display device with an illumination controller for adjusting display illumination according to environmental light intensity detected by a light sensor. Thus, the illumination from the display device is accordingly increased during the day or in a bright environment, and decreased during the night or in a dark environment.
Generally, a light sensor for detecting environmental light generates an output signal according to the intensity of the received light. The output signal as shown in FIG. 7(a) is one single pulse signal. As the intensity of the received light increases, a width T of the pulse signal decreases. In other words, the brighter the environmental light is, the shorter the width of the pulse signal output from the light sensor is. For example, a light sensor is disclosed in Japanese Patent Application Publication No. 2005-345286. In order to detect environmental light intensity, the width T of the pulse signal output from the light sensor where the environmental light has been received is measured. However, as shown in FIG. 7(b), the light sensor is unable to operate normally due to external noises, such that an error may exist in the pulse signal output from the light sensor. Specifically, when the environmental light is dark and the light intensity received by the light sensor is relatively weak, an error is more likely to occur. This is because the pulse duration of the pulse signal output from the light sensor is relatively wider when the environmental light is dark. Specifically, according to the prior art as shown in FIG. 7(c), an error period Te is discarded, and the environmental light intensity is determined by the remaining period (T-Te). As a result, the environmental light intensity determined by discarding the error duration, compared with the measured value, has an approximate 10% error therein.
Therefore, it is desired to provide light intensity detecting methods and devices, and display devices and storage media using the same, detecting light intensity according to pulse duration of a pulse signal output from a light sensor without being affected by noise.